He also advises that the paper should not be afterwards _ironed_, as it is apt to produce flaws and spots on the albumenized surface; and he believes that the chemical action of the nitrate of silver alone is sufficient to coagulate the albumen, without the application of heat. This I have found _in practice_ to be incorrect: for when I have excited albumenized paper, to which a sufficient heat has not been applied, I have invariably observed that a portion of the albumen becomes detached into the silver solution, making it viscid, and favouring its decomposition. Consequently, the sheets _last_ excited seldom retain their colour so long as those which are first prepared. But even laying aside the question of the coagulation of the albumen, the paper, unless it is ironed, remains so "cockled up," that it is not only unsightly, but very difficult to use. 100-grain solution of nitrate of silver (I presume to the ounce) is also recommended. In a late Number, I find DR. DIAMOND uses a 40-grain solution with perfect success; and my own experience enables me to verify this formula as being sufficiently powerful:--no additional intensity of colour being obtained by these strong solutions, it is a mere waste of material. Therefore I think your correspondent fails in effecting either economy of material or time. However painful it may be to me to offer remarks at variance with the opinions of your kind and intelligent correspondents, yet I consider it a duty that yourself and readers should not be misled, and so interesting and elegant an art as photography brought into disrepute by experiments which, however well intentioned, plainly indicate a want of experience. K. N. M. [MR. SHADBOLT'S scientific acquirements appeared to us to demand that we should give insertion to his plan of albumenizing paper: although we felt some doubts whether it did not contain the disadvantages which our correspondent now points out. We had met with such complete success in following out the process recommended by DR. DIAMOND in our 205th Number, that we did not think it advisable to make any alteration. For our own experience has shown us the wisdom, in photography as in other matters, of holding fast that which is good.--ED.] _Stereoscopic Angles._--Notwithstanding the space you have devoted to this subject, I find little practical information to the photographer: will you therefore allow me to presume to offer you my mode, which, regardless of all scientific rules, I find to be perfectly successful in obtaining the desired results? My focussing-glass is ruled with a few perpendicular and horizontal lines with a pencil, and I also cross it from corner to corner, which marks the centre of the glass. These lines always allow me to place my camera level, because the perpendicular lines being parallel with any upright line secures it.